Bank of Montreal is suing a group of lawyers, brokers and a handful of its own employees in what is reportedly one of the biggest mortgage frauds in Canadian history, CBC News is reporting.

According to a story on the CBC website, Canada’s fourth biggest bank was hit by losses of as much as $30-million as the result of a complex scam that took place in Western Canada and involved perpetrators securing mortgages worth significantly more than the homes they were used to buy.

The alleged masterminds reportedly pocketed the difference, transferring much of the money overseas.

A BMO spokesman declined to discuss details of the suit, saying only that no customers were directly impacted and that the information it gained from the experience has enabled it to strengthen its processes and enhance due diligence.

The bank first uncovered the fraud in 2006, obliquely referring to it in the third quarter of 2007 when it reported “higher specific provisions” for bad loans partly because of its Canadian mortgage business.

BMO is suing the alleged perpetrators for $140-million.

According to the CBC, the ringleaders lined up “straw buyers,” often new immigrants to sign documents for inflated home loans, typically for a fee of less than $10,000.

Lawyers then provided documentation asserting that the buyers had sufficient income and savings to afford the mortgages.